Simultaneous retrievals of cloud optical depth and effective radius from Thin-Cloud Rotating Shadowband Radiometer (TCRSR)

The current measurement techniques for cloud optical depth and effective radius are not as accurate as required, especially for the thin clouds with low liquid water content (<100 g/m2). A new technique for simultaneously retrieving cloud optical depth and effective radius has been proposed for optically thin clouds [Min and Duan, 2005]. Based on this technique, a new radiometer, Thin-Cloud Rotating Shadowband Radiometer (TCRSR), is developed, which measures the angular distribution of solar radiation from the sun in six narrow spectral bands. A retrieval algorithm of cloud optical depth and effective radius is developed and tested for TCRSR measurements at the ARM SGP site. Intercomparison of retrievals from TCRSR and MFRSR measurements shows both retrieved cloud optical depth and effective radius are consistent with each other. It demonstrates the utility of simultaneous retrievals of cloud optical depth and effective radius from TCRSR.